Exposed lens retroreflective article

ABSTRACT

An exposed lens retroreflective article that includes a binder layer; a layer of spaced apart optical elements that are partially embedded in the binder layer; a penetrated colored layer that is located between the spaced apart optical elements; and a reflective layer that is located functionally behind the layer of optical elements and the penetrated colored layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 13/114,573, filedMay 24, 2011, which claims priority to International Application No.PCT/CN2010/073217, filed May 25, 2010, the disclosures of which areincorporated herein by reference in their entirety.

FIELD

The present disclosure relates to an exposed lens retroreflectivearticle that includes a colored layer between the lenses and areflective layer behind the lenses.

BACKGROUND

Persons who work or exercise near motor vehicle traffic can be madesafer by wearing clothing that highlights the person's presence topassing motor vehicles. To promote the safety of roadway workers andpedestrians, clothing manufacturers commonly produce bright clothing tomake the wearer more conspicuous. Manufacturers also routinely secureretroreflective articles to the outer surface of the clothing to improvewearer conspicuity. Retroreflective articles are passive devices thatreturn incident light back toward the light source. The articleshighlight a person's presence to motorists at nighttime by reflectinglight from the motor vehicles' headlamps back to the motor vehicledriver. The bright image displayed by the retroreflective articleultimately gives motorists more time to react to the person's presence.

Originally, retroreflective materials were generally all silver incolor. As the need arose for retroreflective articles that were coloredother than silver, the retroreflective nature of the articles suffered.Therefore, there remains a need for colored retroreflective articlesthat have increased retroreflective properties.

BRIEF SUMMARY

Disclosed herein is an exposed lens retroreflective article thatincludes a binder layer; a layer of spaced apart optical elements thatare partially embedded in the binder layer; a penetrated colored layerthat is located between the spaced apart optical elements; and areflective layer that is located functionally behind the layer ofoptical elements and the penetrated colored layer.

Also disclosed is a transfer article that includes an exposed lensretroreflective article that includes a binder layer; a layer of spacedapart optical elements that are partially embedded in the binder layer;a penetrated colored layer that is located between the spaced apartoptical elements; and a reflective layer that is located functionallybehind the layer of optical elements and the penetrated colored layer;and a carrier web into which the layer of optical elements is partiallyembedded.

Disclosed herein is an exposed lens retroreflective article thatincludes a binder layer; a layer of spaced apart optical elements thatis partially embedded in the binder layer; a colored layer that islocated between the spaced apart optical elements, wherein the coloredlayer comprises nanopigment; and a reflective layer that is locatedfunctionally behind the layer of optical elements and the penetratedcolored layer.

Also disclosed is a transfer article that includes an exposed lensretroreflective article that includes a binder layer; a layer of spacedapart optical elements that is partially embedded in the binder layer; acolored layer that is located between the spaced apart optical elements,wherein the colored layer comprises nanopigment; and a reflective layerthat is located functionally behind the layer of optical elements andthe penetrated colored layer; and a carrier web into which the layer ofoptical elements is partially embedded.

Also disclosed is a method of making an exposed lens retroreflectivearticle that includes the steps of partially embedding a plurality ofoptical elements in a carrier web; applying a color composition to theexposed surfaces of the optical elements, wherein the color compositionincludes pigment having an average size from about 1 nm to about 1000nm; at least one polymer; and a low flash point solvent; applying areflective material to the exposed surfaces of the optical elements andthe applied color composition; and applying a binder composition to forma binder layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments of the disclosurein connection with the accompanying drawings, in which:

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

FIG. 1A is a cross-sectional view of an exposed lens retroreflectivearticle as disclosed herein; FIG. 1B is a top down view of the exposedlens retroreflective article of FIG. 1A; FIG. 1C is a cross-sectionalview of an exposed lens retroreflective article as disclosed herein;FIG. 1D is a cross-sectional view of an exposed lens retroreflectivearticle that includes an optional clear layer disposed on the coloredlayer as disclosed herein; FIG. 1E is a cross-sectional view of anexposed lens retroreflective article that includes an optional clearlayer disposed between the colored layer and the reflective layer asdisclosed herein; and FIG. 1F is a cross-sectional view of an exposedlens retroreflective article that includes two optional clear layers asdisclosed herein;

FIG. 2 is a cross-sectional view of an exposed lens retroreflectivearticle that includes a substrate as disclosed herein;

FIG. 3 is a schematic three dimensional view of a portion of an exposedlens retroreflective article as disclosed herein;

FIG. 4 is a cross-sectional view of a transfer sheet that includes anexposed lens retroreflective article as disclosed herein;

FIG. 5 illustrates an article of clothing that displays aretroreflective article as disclosed herein;

FIG. 6A is an optical micrograph of the reflective surface of opticalelements prepared according to Example 1;

FIG. 6B is a graph depicting the brightness of Examples 1 and 2 after 0,5, 10, and 15 washing cycles;

FIG. 7 is a graph depicting the brightness of the articles of Examples 3through 7 as a function of pigment loading; and

FIG. 8 is a graph depicting color analysis of Examples 2, 4, 8, and 9.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawing that forms a part hereof, and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present disclosure. The followingdetailed description, therefore, is not to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

Disclosed herein are retroreflective articles. Embodiments of disclosedretroreflective articles can offer advantages because they are coloredbut still offer high reflectivities. Disclosed retroreflective articlescan offer such advantages because of the combination of partiallyembedded optical elements and a penetrated colored layer positionedbetween the partially embedded optical elements. Disclosedretroreflective articles can also pass various standard brightnesstests, such as EN471 and ANSI 107 for example. Disclosed retroreflectivearticles can also have good color chroma. “Good color chroma” can referto the color coating have less dark or black tones which can be causedby the color of a vapor coated metal reflective layer (vapor coatedmetal reflective layers such as Al or Ag generally appear as a graycolor). Disclosed retroreflective articles can also have less angle ofobservation dependent difference in color (for example less differencefrom a vertical angle or less difference when squinting).

An exemplary retroreflective article is schematically depicted in FIG.1A. The retroreflective article 10 depicted in FIG. 1A includes opticalelements 12. The optical elements 12 can generally be spaced apart. Thephrase spaced apart, as used herein means that the optical elements 12are not touching each other and a void or space remains between eachoptical element 12 and the next optical element 12. The optical elements12 are partially embedded in or supported by the binder layer 14. Theoptical elements 12 can be described as being present as a layer ofoptical elements 12.

The retroreflective article 10 also includes a colored layer 18. Thecolored layer 18 can be described as being penetrated by the opticalelements 12. FIG. 1B shows a top down view of the article of FIG. 1A. Asseen there, the colored layer 18 is penetrated by the optical elements12. The colored layer 18 is located at least between the spaced apartoptical elements 12. As seen in both FIGS. 1A and 1B, a portion of eachoptical element 12 extends beyond the colored layer 18 and is exposed.

The retroreflective article 10 also includes a reflective layer 16. Thereflective layer 16 is positioned between the colored layer 18 and theoptical elements 12 and the binder layer 14. The position of thereflective layer 16 can also be described as being bound by the coloredlayer 18 and the optical elements 12 on one surface and the binder layer14 on the opposing surface. The reflective layer 16 can also bedescribed as being located functionally behind the optical elements 12and the penetrated colored layer 18 and functionally in front of thebinder layer 14. The reflective layer 16 need not be present on theentirety of the article. In embodiments, one or a plurality of regionson the article need not have the reflective layer 16. Such an embodimentwill have regions of the article that are not reflective and regions ofthe article that are reflective; the reflective layer can be patterned.The reflective and non-reflective regions of an article can be utilizedfor example to form indicia as desired.

The optical elements 12 and the reflective layer 16 operate together toreturn a substantial quantity of incident light back towards the sourceof the incident light. Incident light I that strikes the front surfaceof the retroreflective article 10 passes sequentially through theoptical elements 12 to be reflected by the reflective layer 16 to againenter the optical element 12, where the light's direction is thenaltered to return toward the light source as denoted by beam R.

FIG. 1C shows another exemplary embodiment of a disclosed article. Thearticle 11 can also include pigment clusters 52 that can be present onthe surface of the optical elements between the optical element 12 andthe reflective layer 16. The pigment clusters 52 are not drawn to scale,and no assumptions regarding the size or relative distribution of thepigment clusters should be assumed. The pigment clusters 52 that can bepresent on the optical elements 12 can generally be unevenly distributedacross the back surface of the optical element 12. In embodiments, notall optical elements have pigment clusters on the surface thereof. Inembodiments, at least one optical element has at least one pigmentcluster on the surface thereof. In embodiments, a substantial amount ofthe optical elements have at least one pigment cluster on the surfacethereof. The pigment clusters 52 on the back surface of the opticalelement 12 can be characterized as an extension of the colored layer 18.If such characterization is utilized, the pigment clusters 52 can becharacterized as a discontinuous extension of the colored layer 18.Alternatively, the pigment clusters 52 can be characterized as beingpart of the colored layer 18 that are penetrated by the optical elements12.

The presence of the pigment 52 on the back surface of the opticalelements 12 can, but need not, be due to the way in which the articlewas made. Therefore, the amount of pigment 52 that may be present on theback surface of the optical element 12 can be controlled or modifiedbased on various processing conditions. The presence of the pigment 52on the back surface of the optical elements can form a visibly mattesurface when the article is viewed (through a microscope). The pigment52 can also decrease the dependence of the color on the viewing angle.

Another embodiment of a disclosed article is depicted in FIG. 1D. Thearticle 13 depicted in FIG. 1D includes components similar to those ofFIGS. 1A through 1C, which are numbered similarly. Although not depictedin FIG. 1D, it should also be noted that the exemplary article 13 caninclude pigment clusters similar to pigment clusters 52 shown in FIG.1C. The article 13 includes an optional clear layer 19. Optional clearlayer 19 (or multiple clear layers) may have any useful thicknesses. Inembodiments, a clear layer may be from about 0.01 um to about 20 umthick. The clear layer 19 can be a continuous layer, may bediscontinuous (for example, penetrated by the optical elements), or acombination thereof.

As seen in this exemplary article, the clear layer 19 is disposed on thecolored layer 18. The optional clear layer 19 can generally function toincrease or enhance the durability of the articles. The clear layer 19depicted in FIG. 1D (located on the colored layer 18 or with respect toFIG. 4, between the colored layer 18 and optical elements 12 and theheat softenable polymer layer 34) can also function to maintain theoptical elements in the article when the color composition is applied toform the colored layer. In embodiments, the optional clear layer 19 canbe coated using methods similar to those above (e.g., spray coatingmethods). The optional clear layer 19 can be made of polymericmaterials. Specific polymeric materials can include for example polymerssuch as those utilized in the colored layer.

FIG. 1E depicts another exemplary article 15. The article 15 can includecomponents similar to those depicted in the articles shown in FIG. 1Athrough 1D (including components similar to pigment clusters 52 eventhough not depicted in FIG. 1E). The article 15 differs from the article13 in that the clear layer 19 is disposed between the colored layer 18and the reflective layer 16 instead of on the colored layer 18. Theoptional clear layer 19 can provide functionality as discussed above andcan be made from the same components as those discussed above.

FIG. 1F depicts yet another exemplary article 17. Article 17 can includecomponents similar to those depicted in the articles shown in FIG. 1Athrough 1E (including components similar to pigment clusters 52 eventhough not depicted in FIG. 1F). The article 17 differs from thearticles 13 and 15 in that there are two clear layers 19 a and 19 b. Thecolored layer 18 is generally disposed between the two clear layers 19 aand 19 b. The optional clear layers 19 a and 19 b can providefunctionality as discussed above and can be made from the samecomponents as those discussed above. The clear layers 19 a and 19 b mayor may not be the same thicknesses and may or may not be made from thesame materials.

FIG. 2 shows another embodiment of a retroreflective article 15 thatoptionally includes a substrate 20. The optional substrate 20 canprovide the article with enhanced structural integrity. The substrate 20can be fabric, a film, or scrim, if utilized. If a substrate isutilized, a layer of adhesive may be applied to the substrate 20 toeasily adhere the article to an item of interest.

As discussed above, the optical elements 12 are partially embedded inthe binder layer 14 and penetrate the colored layer 18. Each opticalelement 12 can be described as having three different regions. Thesethree regions are depicted in FIG. 3. The first region is the exposedregion 12 a. The exposed region 12 a of an optical element is the regionabove the top surface of the colored layer 18. The second region is thecolored contact region 12 b. The colored contact region 12 b of anoptical element is the region that contacts the colored layer 18. Thecolored contact region 12 b can generally be characterized as beingbelow the exposed region 12 a. The third region is the reflectivecontact region 12 c. The reflective contact region 12 c of an opticalelement is the region that contacts the reflective layer 16. Thereflective contact region 12 c can generally be characterized as beingbelow the colored contact region 12 b.

The colored contact region 12 b can be characterized as having a colorcontact surface area, which can be the surface area of an opticalelement 12 that is in contact with the colored layer 18. As the colorcontact surface area decreases, more space will be available on the backof the optical element from which to reflect light back out through theoptical element, thereby increasing the retroreflective nature of thearticle. The color contact surface area can be characterized by actualvalues of the surface area, or in relation to the surface area of theentire optical element. In embodiments, the color contact surface areacan be from about 0.5% to 75% of the total surface area of the opticalelement. In embodiments, the color contact surface area can be fromabout 5% to 50% of the total surface area of the optical element. Inembodiments, the color contact surface area can be from about 10% to 45%of the total surface area of the optical element.

The reflective contact region 12 c can be characterized as having areflective contact surface area, which is the surface area of theoptical element 12 that is in contact with the reflective layer 16. Asthe reflective contact surface area decreases, there will be less spaceon the back of the optical element from which to reflect light back outthrough the optical element, and the retroreflective nature of thearticle will decrease. The reflective contact surface area can becharacterized by actual values of the surface area, or in relation tothe surface area of the entire optical element. In embodiments, thereflective contact surface area can be at from about 0.1% to 75% of thetotal surface area of the optical element. In embodiments, thereflective contact surface area can be from about 5% to 50% of the totalsurface area of the optical element. In embodiments, the reflectivecontact surface area can be from about 10% to 45% of the total surfacearea of the optical element.

The binder layer can include a polymer and may contain other materials.The binder layer adheres to or is otherwise physically associated withthe reflective layer. In embodiments, the binder layer can also adhereto or be otherwise physically associated with an adhesive layer or abacking of some sort (for example, fabric, a film, or scrim). The binderlayer is capable of supporting optical elements and is typically acontinuous, fluid-impermeable, polymeric, sheet-like layer. Binderlayers that are too thin may be too thin to adhere to both a substrateand the optical elements. Binder layers that are too thick mayunnecessarily stiffen the article and add to the cost. In embodiments,the binder layer has an average thickness of about 1 to 250 micrometers.In embodiments, the binder layer has an average thickness of about 30 to150 micrometers.

The binder layer may include polymers that contain units such asurethane, ester, ether, urea, epoxy, carbonate, acrylate, acrylic,olefin, vinyl chloride, amide, alkyd, or combinations thereof. A varietyof organic polymer forming reagents can be used to make the polymer.Polyols and isocyanates can be reacted to form polyurethanes; diaminesand isocyanates can be reacted to form polyureas; epoxides can bereacted with diamines or diols to form epoxy resins, acrylate monomersor oligomers (it should be noted that any time a monomer is mentionedherein as being utilized, an oligomer can also be utilized) can bepolymerized to form polyacrylates; and diacids can be reacted with diolsor diamines to form polyesters or polyamides. Examples of commerciallyavailable polymer forming reagents that may be used in forming thecolored layer include for example: Vitel™ 3550 available from BostikInc., Middleton, Mass.; Ebecryl™ 230 available from UBC Radcure, Smryna,Ga., Jeffamine™ T-5000, available from Huntsman Corporation, Houston,Tex.; CAPA 720, available from Solvay Interlox Inc., Houston Tex.; andAcclaim™ 8200, available from Lyondell Chemical Company (formerly ArcoChemical Co.), Houston, Tex. Examples of reactive polymers useful informing the binder layer include hydroxyalkylenes, polymeric epoxidessuch as polyalkylene oxides, and copolymers thereof.

The polymer precursor can also include an acrylate monomer or acrylateoligomer as a reactive diluent such that the acrylate monomerpolymerizes via free-radical polymerization and the other reactivecomponents such as polyols and isocyanates polymerize via a condensationpolymerization. The polymerizations may occur contemporaneously. Thereactive diluent allows for a higher solids loading level without theviscosity problems associated with handling higher viscosity solutions.It also eliminates the need for solvent and the problems associated withremoving the solvent.

The polymer that is used in the binder layer may have functional groupsthat allow the polymer to be linked to a silane coupling agent, or thereactants that form the polymer may possess such functionality. Forexample, in producing polyurethanes, the starting materials may possesshydrogen functionalities that are capable of reacting with anisocyanate-functional silane coupling agent; see, for example, U.S. Pat.No. 5,200,262 to Li.

In embodiments, compositions such as those discussed by Crandall in U.S.Pat. No. 5,645,938 and International Publication WO 96/16343 and byFleming in U.S. Pat. No. 5,976,669 and PCT published application WO98/28642.

The binder layer can also optionally include other materials notdiscussed herein. In embodiments, a binder layer may be made from about,in weight percent, 55% Capa™ 720 (a block copolymer ofpoly(tetramethylene glycol) and polycaprolactone), 16.4% ethoxylatedbisphenol A diol, 4.4% ethoxylated trimethylolpropane, 4.1%isocyanatotriethoxysilane, 20.4% methylene-bis-diphenyl diisocyanate,and catalytic amounts of tertiary amine and dibutyltindilaurate.

Optical elements that can be utilized in retroreflective articles asdisclosed herein can include microspheres. In embodiments, themicrospheres are substantially spherical in shape to provide uniform andefficient retroreflection. The microspheres can also be highlytransparent to minimize light absorption so that a large percentage ofincident light is retroreflected. The microspheres are oftensubstantially colorless but may be tinted or colored in some otherfashion (see, for example, U.S. Pat. No. 3,294,559 to Searight et al. orU.S. Pat. No. 5,286,682 to Jacobs et al.). The microspheres may be madefrom glass, a non-vitreous ceramic composition, or a synthetic resin. Inembodiments, glass and ceramic microspheres can be utilized because theytend to be harder and more durable than microspheres made from syntheticresins. Examples of microspheres that may be useful in this inventioninclude for example those found in U.S. Pat. Nos. 1,175,224, 2,461,011,2,726,161, 2,842,446, 2,853,393, 2,870,030, 2,939,797, 2,965,921,2,992,122, 3,468,681, 3,946,130, 4,192,576, 4,367,919, 4,564,556,4,758,469, 4,772,511, and 4,931,414.

Useful microspheres can have average diameters of about 30 to 200micrometers, and in embodiments, they can have average diameters ofabout 50 to 150 micrometers. Microspheres smaller than this range tendto provide lower levels of retroreflection, and microspheres larger thanthis range may impart an undesirably rough texture to theretroreflective article or may undesirably reduce its flexibility.Useful microspheres can typically have a refractive index of about 1.2to 3.0, in embodiments about 1.6 to 2.2, and in still other embodimentsabout 1.7 to 2.0.

The colored layer can include polymer material and pigments. Generally,polymeric materials such as those described above with respect to thebinder layer can be utilized. Specific exemplary polyurethane formingmethods (into which pigments can be incorporated) are described byCrandall in U.S. Pat. Nos. 5,645,938 and 6,416,856 and PCT publishedapplication WO 96/16343, and Fleming in U.S. Pat. No. 5,976,669, and PCTpublished application WO 98/28642. In embodiments, polyesterpolyurethanes, polyether polyurethanes, or polyurethanes that include ablock copolymer of polyether and polyester units can be utilized in thecolored layer. A commercially available polyurethane material that canbe utilized in the colored layer includes Bayhydrol® polyurethanedispersions that are available from Bayer AG (Leverkusen, Germany).

A pigment can be any material that is capable of changing the color ofreflected or transmitted light as the result of wavelength-selectiveadsorption. Any colored pigment can be utilized in retroreflectivearticles as disclosed herein. In embodiments, the pigment can be ananopigment. A nanopigment is a pigment that generally has an averageparticle size in the nanometer range. In embodiments, a nanopigment canhave an average particle size from about 1 nm to about 1000 nm.Nanopigments can be useful because of the interaction of light withthem; light will diffract from nanopigments because of their size, whichcan contribute to high reflectivities. In embodiments, a nanopigment canhave an average particle size from about 50 nm to about 500 nm. Anexemplary nanopigment that can be utilized includes Cabojet 300, whichis commercially available from Cabot Corporation (Boston, Mass.).

In embodiments, the colored layer can include both nanopigments andother sized pigments (which can be referred to herein as “normalpigments”). Normal pigments can generally have average particle sizesfrom about 1 μm to about 40 μm. In embodiments, normal pigments can haveaverage particle sizes from about 1 μm (1000 nm) to about 10 μm. Inembodiments that include both nanopigments and normal pigments, thenanopigments can account for at least about 5% of the total pigment byweight. In embodiments that include both nanopigments and normalpigments, the nanopigments can account for at least about 10% of thetotal pigment by weight. In embodiments, the colored layer can includeboth pigments and dyes. In embodiments, the colored layer can includeboth nanopigments and dyes for example.

The colored layer can generally include a desirable amount of pigment toprovide a desired color or depth of color of the colored layer orarticle. The amount of pigment in the colored layer can depend at leastin part on the particular pigment(s) utilized, the desired color orshade of color, the other components in the colored layer, andcombinations thereof. In embodiments, the colored layer can have 0.1 to70% pigment, by weight of solids in the colored layer; from 1 to 40%pigment, by weight of solids in the colored layer; or from 5 to 35%pigment, by weight of solids in the colored layer.

The colored layer (and the binder layer) can also optionally includeother materials not discussed herein. For example, other ingredientssuch as fillers, stabilizers (for example, thermal stabilizers andantioxidants such as hindered phenols and light stabilizers such ashindered amines or ultraviolet stabilizers), flame retardants, flowmodifiers (for example, surfactants such as fluorocarbons or silicones),plasticizers, UV resistant components (for example, UV resistantfillers), and elastomers may be utilized in either or both the coloredlayer and binder layer. Care should be taken when selecting suchadditives because some may detrimentally affect laundering durability.For example, high levels of flame retardants such as melaminepyrophosphate may have a deleterious effect on the article'sretroreflective performance after laundering.

The colored layer can generally include the pigment dispersed in thepolymeric material. Various methods of forming the colored layer from acomposition including the pigment and the polymeric material can beutilized to form the colored layer. The methods discussed below offerfurther discussion regarding specific types of ways of forming thecolored layer from a colored layer composition. The colored layer neednot be present on the entirety of the article. For example, the colorcomposition can be printed onto the article in order to form someindicia with the regions of the article that appear colored; the coloredlayer can be patterned. This can be accomplished by printing the colorcomposition onto an article containing the optical elements.

The colored layer can have an average thickness that is less than theaverage diameter of the optical elements (in the case of sphericaloptical elements). In embodiments, the colored layer can have an averagethickness that is from about 0.0005 to about 0.75 the average diameterof the optical elements. In embodiments, the colored layer can have anaverage thickness that is from about 0.05 times the average diameter ofthe optical elements to about 0.5 times the average diameter of theoptical elements.

Disclosed articles also include a reflective layer. The reflective layercan generally be a layer of material that has a relatively high lightrefraction index. In embodiments, the reflective layer is a layer ofmaterial with a light refraction index of at least 2.2. In embodiments,the reflective layer can be a specularly reflective layer. Inembodiments, the reflective layer can be about 50 to 500 nanometersthick.

In embodiments, the reflective layer can be a metal reflective layer. Asused herein, the term “metal reflective layer” refers to a layer thatincludes elemental metal in pure or alloy form which is capable ofreflecting light. The metal may be a continuous coating produced byvacuum deposition, vapor coating, chemical deposition, or electrolessplating for example. In embodiments, vapor coating can be used becauseit is economical, and the vapor deposited coating can have particularlygood performance as a reflector. Exemplary metals include for examplealuminum (Al), silver (Ag), chromium (Cr), nickel (Ni), magnesium (Mg),gold (Au), tin (Sn), and the like, in elemental form. In embodiments,aluminum and silver can be used because they tend to provide goodretroreflective brightness. In the case of aluminum, some of the metalmay be in the form of the metal oxide or metal hydroxide.

A variety of non-metallic materials may also be used to provide areflective layer. Exemplary materials include for example cryolite andTiO₂. In embodiments, the reflective layer could include more than onelayer of materials. For example, a reflective layer could include a twolayer (or more) structure made from zinc sulfate (ZnS) and cryolite,such as that exemplified in GB Patent No. 1447585.

In embodiments, retroreflective articles as disclosed herein can exhibitnumerous desirable properties. In embodiments, disclosed retroreflectivearticles can pass various industry standards for retroreflectiveness.For example, disclosed retroreflective articles can pass AmericanNational Standards Institute (ANSI) standards such as ANSI/ISEA107-1999; ANSI/ISEA 107-2004 (updated version of ANSI/ISEA 107-1999),ANSI/ISEA 207-2006, ANSI/ISEA 107-2010; or European Standards such asEN471 for example.

In embodiments, retroreflective articles as disclosed herein can exhibitretroreflectivity of at least a certain amount when measured using theRetroreflective Brightness procedure described below. In embodiments,retroreflective articles as disclosed herein can exhibitretroreflectivity of at least about 50 candelas/lux/meter² at 5/0.2angle when measured using the Retroreflective Brightness proceduredescribed below. In embodiments, retroreflective articles as disclosedherein can exhibit retroreflectivity of at least about 250candelas/lux/meter² at 5/0.2 angle when measured using theRetroreflective Brightness procedure described below. In embodiments,retroreflective articles as disclosed herein can exhibitretroreflectivity of at least about 330 candelas/lux/meter² at 5/0.2angle when measured using the Retroreflective Brightness proceduredescribed below.

Disclosed retroreflective articles can also exhibit good washingperformance, which indicates that they retain at least some portion oftheir retroreflective properties after being washed. In embodiments, adisclosed retroreflective article can retain at least about 100candelas/lux/meter² at 5/0.2 angle after being washed 15 times. Inembodiments, a disclosed retroreflective article can retain at leastabout 200 candelas/lux/meter² at 5/0.2 angle after being washed 15times. In embodiments, a disclosed retroreflective article can retain atleast about 300 candelas/lux/meter² at 5/0.2 angle after being washed 15times.

Also disclosed herein are transfer articles. An exemplary transferarticle is depicted in FIG. 4. A transfer article 30 can include aretroreflective article 22 that can optionally include a substrate 20 asdisclosed with respect to FIG. 2. The transfer article 30 can alsoinclude a carrier web 32. The carrier web 32 can include a heatsoftenable polymer layer 34 on a carrier 36. The carrier 36 can be forexample, a paper sheet or a film. Examples of the heat softenablepolymer layer 34 can include for example polyvinyl chloride; polyolefinssuch as polyethylene, polypropylene, and polybutylene; and polyesters.The layer of optical elements 12 can be partially embedded into the heatsoftenable polymer layer 34 of the carrier web 32.

A retroreflective article or a transfer sheet containing aretroreflective article can be applied to further substrates usingmechanical methods such as sewing. In some applications, however, it isdesired to secure the article to the substrate by an adhesive layer (notshown). The adhesive layer can be, for example, a pressure-sensitiveadhesive, a heat-activated adhesive, or anultraviolet-radiation-activated adhesive. The substrate bearing theretroreflective article can be located on the outer surface of anarticle of clothing, enabling the retroreflective article to bedisplayed when the clothing is worn in its normal orientation on theperson. The substrate may be, for example: a woven or nonwoven fabricsuch as a cotton fabric; a polymeric layer including nylons, olefins,polyesters, cellulosics, urethanes, vinyls, acrylics, rubbers; leather;and the like.

FIG. 5 illustrates a safety vest 40 that displays retroreflectivearticles 42 that are in the form of an elongated sheeting or strip,typically one to three inches wide. The retroreflective stripes may bebounded by fluorescent stripes as described in U.S. Pat. No. 4,533,592to Bingham and U.S. Pat. No. 6,153,128 to Lightle et al. Safety vestsoften are worn by road construction workers to improve their visibilityto oncoming motorists. These kinds of vests frequently become dirty andtherefore need to be able to withstand harsh cleaning conditions so thatthe vest can be reused a number of times. Although a safety vest 40 hasbeen chosen for illustration, the article of clothing may come in avariety of forms. As the term is used herein, “article of clothing”means a launderable item of wearing apparel sized and configured to beworn or carried by a person. Other examples of articles of clothing thatmay display retroreflective articles include shirts, sweaters, jackets(e.g. firefighters' jackets), coats, pants, shoes, socks, gloves, belts,hats, suits, one-piece body garments, bags, and backpacks for example.

Also disclosed herein are methods of making retroreflective articles.The first step in an exemplary method of making a retroreflectivearticle includes partially embedding a plurality of optical elements ina carrier web. Generally, the heat softenable polymer layer retains theoptical elements in the desired arrangement. Carrier webs as discussedabove can be utilized in disclosed methods. Generally, the opticalelements can be partially embedded in the carrier web by commonlyutilized methods, such as cascading the optical elements onto thecarrier web in a desired temporary arrangement. In embodiments, theoptical elements may be arranged in a desired fashion on the carrier webby printing, screening, cascading, or with a hot can roll. For furtherdiscussion of applying microspheres to the carrier web, see U.S. Pat.Nos. 4,763,985; 5,128,804; and 5,200,262. The optical elements can bepartially embedded in the carrier web to about 30 to 60 percent of theoptical element's diameter (assuming a spherical optical element). Theportions of the optical elements that are not embedded in the carrierweb, the exposed surfaces of the optical elements, protrude from the webso that they can receive the colored layer in the next step.

The method can also include optional steps of conditioning the carrierweb or applied optical elements by applying release agents or adhesionpromoters to achieve desired release properties. This optional step canbe carried out before, after, during or a combination thereof, theoptical elements are partially embedded in the carrier web.

The next step in an exemplary method is to apply a color composition tothe exposed surfaces of the optical elements. The color composition caninclude pigment (as discussed above), and at least one polymer ormonomer. In embodiments that utilize monomer (instead of polymer), apolymerization initiator can also be included which can cause themonomer to polymerize. For example, UV curable coatings or UV curableinks can be utilized. UV curable coatings (or inks) can includemonomers, such as acrylate monomers for example, and one or morephotoinitators.

The color composition can also include one or more solvents. Inembodiments, the color composition can include a combination of a lowflash point solvent and a higher (relative to the low flash pointsolvent) flash point solvent. Use of such solvent combinations in thecolor composition can cause less of the color composition to remain onthe top of the optical elements after the color composition is appliedto the exposed surfaces of the optical elements. Instead, the colorcomposition flows down the exposed surfaces of the optical elements andfills the volume between the optical elements and the carrier web inwhich they are embedded. This can be advantageous because colorcomposition that remains on the top surfaces of the optical elements caninterfere somewhat with the effect of the reflective layer on the backsof the optical elements and decrease the retroreflective nature of thearticle. Even in embodiments where pigment clusters (such as seen inFIG. 1C) exist, use of nanopigments can reduce the decrease inreflectivity that may be caused by such pigment clusters on the backsurfaces of the optical elements.

Embodiments that utilize the combination of a low flash point solventand a higher flash point solvent can minimize the amount of the colorcomposition (or pigment) that remains on the back surface of the opticalelements (as depicted in FIG. 1C). This is thought to be accomplished bythe color composition flowing down the exposed surfaces of the opticalelements and filling the voids between the optical elements and thebinder layer in which they are embedded. The pigment (illustrated as thepigment 52 in FIG. 1C) that remains on the back surfaces of the opticalelement (which surface can also be referred to as the reflective contactsurface 12 c, see FIG. 3) can be advantageous in embodiments because itcan reduce the color difference that can be seen at vertical viewingangles or a “squinting view”.

In embodiments, the difference between the flash point of the twosolvents (the low flash point solvent and the higher flash pointsolvent) can be at least about 10° C. In embodiments, the differencebetween the flash point of the two solvents can be at least about 30° C.Exemplary solvent combinations include for example ethanol and water;ethyl acetate and toluene; and methyl ethyl ketone and toluene.

In embodiments that utilize a low flash point solvent and a higher flashpoint solvent, the low flash point solvent can account for about 10% to95% by weight of the total solvent. In embodiments, the low flash pointsolvent can account for about 30% to 90% by weight. In embodiments, thelow flash point solvent can account for about 50% to 80% by weight.

The color composition can also include a solvent and a polymer that isflowable at room temperature or at temperatures from 20° C. to 80° C.Such a combination can allow color composition to flow down the exposedsurfaces of the optical element both before the solvent is flashed offand after (due to the flowable polymer component). This allows the colorcomposition to continue flowing down the exposed surfaces of the opticalelements during curing, which can allow a significant portion of thecolor composition to aggregate between the optical elements instead ofremaining on the back surfaces of the optical elements. In suchembodiments, the solvent could include, for example, ethyl acetate,methyl ethyl ketone, acetone, toluene, tetrahydrofuran, or dimethylformamide. In such embodiments, the polymer could include for example,acrylate polymers, epoxy liquids, silicone liquids, or polyols forforming polyurethanes and isocyanates as described above.

The polymer can generally include polymers as discussed above, monomersor oligomers to form the polymers as discussed above, or a combinationthereof. In embodiments, more than one specific polymer can be utilizedin a color composition. In embodiments, the polymer can be utilized as adispersion of the polymer in water. In embodiments, the polymer can beutilized as a flowable liquid that has a viscosity of from about 10 to10,000 centipoise (cps). In embodiments, the polymer can be utilized asa flowable liquid that has a viscosity of from about 10 to 4,000 cps.

Color compositions containing at least pigment, polymer, and a solventcan be made using commonly utilized techniques. In embodiments, colorcompositions can generally contain from about 0.1 to 70 wt % of pigment(based on solids), in embodiments from 1 to 40 wt % pigment (based onsolids), and in embodiments from 5 to 35 wt % pigment (based on solids).In embodiments, color compositions can generally contain from 30 to 99.9wt % of polymer (based on solids), in embodiments from 60 to 99 wt %polymer (based on solids), and in embodiments from 65 to 95 wt % polymer(based on solids).

The color composition can also optionally include other componentsincluding for example, water (which may be added as part of a polymerdispersion or separately), other solvents, crosslinkers, catalysts,defoamers, and surfactants for example. Such other components cangenerally be used for reasons and in quantities as would be known to oneof skill in the art having read this specification.

The color composition can generally be applied to the exposed surfacesof the optical elements using known techniques of applying a liquid.Exemplary methods include for example spray coating, bar coating, andprinting. In embodiments, printing methods can be utilized to apply thecolor composition across less than the entirety of the article, forexample to form desired indicia using colored and non-colored regions ofthe article.

The amount of the color composition applied to the exposed surface ofthe optical elements can be controlled using known techniques, which canvary depending on the method of application. In embodiments, thequantity of color composition applied to the exposed surface of theoptical elements can be controlled by comparing the brightness of thepartially embedded optical elements before and after application of thecolor composition. As the quantity (coating weight) of color compositionincreases, the brightness of the partially embedded optical elementsdecreases. This is generally true because as the amount of colorcomposition increases, the surface area of the optical elements thatremains exposed decreases. Once partially embedded, the exposed surfacearea is responsible for the retroreflective nature of the opticalelements and therefore the brightness of the optical elements. Thechange in brightness of the partially embedded optical elements withoutcolor composition to once coated with color composition can be utilizedto manage the coating weight of the color composition.

In methods where it is desired to monitor, control, or both the coatingweight of the color composition, the brightness of the partiallyembedded optical elements can be evaluated before the color compositionis applied. The brightness of the partially embedded optical elementscan then be evaluated after at least a portion of the color compositionhas been applied. The difference in brightness can be utilized todetermine whether additional color composition should be applied. Inembodiments, this can be an iterative process, where the brightness istested, more color composition is applied, and the steps are repeateduntil the desired amount (for example coating weight) of colorcomposition has been applied as determined by the change in brightness.Testing the brightness of uncoated, partially coated, or fully coatedpartially embedded optical elements can be accomplished using knownmethods and apparatus' for testing the brightness of retroreflectivesurfaces.

Disclosed methods also include the step of applying reflective material(as discussed above) to the exposed surfaces of the optical elements andthe applied color composition. Once the color composition has beenapplied and has at least partially filled the voids between the opticalelements to form the colored layer, a reflective material can be appliedto form the reflective layer. Generally, the reflective material isapplied to the surface of the colored layer opposite the carrier web andthe exposed surfaces of the optical elements opposite the carrier web.The reflective material can be deposited using techniques known to oneof skill in the art, having read this specification. Exemplarytechniques include for example chemical vapor deposition (CVD), vacuumdeposition, vapor coating, or electroless plating. In embodiments, thereflective material can be applied using vacuum deposition.

After the reflective material has been deposited to form the reflectivelayer, a next step can include application of a binder composition toform the binder layer. The binder composition can include components aswere discussed above and can be applied using methods similar to thosefor applying the color composition.

Disclosed methods can also include an optional step of mechanicallyagitating the article once the color composition has been applied(either in whole or in part). Such a step, if undertaken, can cause oraid in the color composition flowing down the exposed surfaces of theoptical elements towards the voids between the optical elements.Generally, articles as formed herein are desired to have the coloredlayer between or surrounding the optical elements but not on the exposedsurfaces of the optical elements, as that will eventually be covered bythe reflective layer. The optional step of mechanically agitating thearticle can assist in getting the color composition to exist between theoptical elements but not on the exposed surfaces of the opticalelements. The step of mechanically agitating the article can also bereferred to a as leveling. The step of mechanically agitating cangenerally be accomplished using techniques known to those of skill inthe art, having read this specification.

Disclosed methods can also include an optional step or steps of curing.In embodiments, the binder composition, the color composition, or bothcan be cured. In embodiments, the binder composition, the colorcomposition, or both can cure without further intervention. Inembodiments, curing can be accomplished using heat, radiation treatment,or some combination thereof. In embodiments, the color composition canbe partially cured or completely cured before the reflective material isapplied. In embodiments, the color composition can be partially cured orcompletely cured after the reflective material is applied. Inembodiments, the binder composition can be partially cured or completelycured once applied. In embodiments, the color composition can bepartially cured or completely cured after an optional substrate (see 20in FIG. 4) is applied to the binder layer on the side opposite thereflective layer. In embodiments, the colored composition and the bindercomposition can be partially cured or completely cured at the same timeor at different times.

EXAMPLES Materials and Methods

All chemicals utilized herein were utilized as received withoutpurification or further processing unless noted otherwise. The chemicalswere obtained as noted below. Ancamine K-54 (catalyst) was obtained fromAir Products and Chemicals, Inc. (Allentown, Pa.). Bayhydrol XP2470(polyurethane dispersion), Bayhydrol® VPLS 2058, Desmodur® 2655(diisocyanate polymer), Desmodur® NZ1 (hexamethylene diisocyanate (HDI)and isopohorone diisocyanate (IPDI) resin), and Desmophen®(hydroxyl-bearing polyester) were obtained from Bayer MaterialScienceLLC (Pittsburgh, Pa.). BiCat® 8108 a bismuth (Bi) catalyst was obtainedfrom Shepherd Chemical Company (Norwood, Ohio). CAB-O-JET® 250C (a cyanpigment dispersion) and CAB-O-JET® 300 (a black pigment dispersion) wereobtained from Cabot Corporation (Boston, Mass.). Dow Corning® Z-6011silane was obtained from Dow Corning, Inc. (Midland, Mich.). Dynasylan®1122 (silane) was obtained from Evonik Industries AG (Essen, Germany).JColor® 10D (a fluorescent yellow pigment dispersion) and JColor® 12 (afluorescent red-orange pigment dispersion) were obtained from J ColorChemical Co., Ltd (Hangzhou, China). NeoCryl® CX100 (an azopyridineemulsion) was obtained from DSM NeoResins (Waalwijk, Netherlands).Vitel® 3580 (a polyester solution) was obtained from Bostik Company(Wauwatosa, Wis.).

Analysis Methods

Reflectivities of samples were measured using EN471 or ANSI107-2004.Initial Reflectivities were measured using ASTM E808 & E809. The colorwas tested using ASTM E1164-9.4. Washing tests were done by followingISO 6330 Method 2A. Color layer distribution analysis was done using anormal optical microscope with a magnification of 200×.

Examples 1 and 2

Paper having a weight of 220 g/m² was coated (at a coating weight of 20g/m²) with a layer of polyethylene adhesive. The article that includedthe paper and the adhesive is an example of the carrier web 32, seen inFIG. 4, which is made up of the paper (carrier 36) and the polyethylene(heat softenable adhesive 34). The adhesive coated paper was pre heatedat 165° C. for about 1 minute, then a quantity of ceramic beads(diameter of about 60 um) were poured thereon to cover the entiresurface of the adhesive coated paper. The article was then heated for anadditional 2 minutes to allow the beads to sink about half way (abouthalf the diameter of the beads sunk in) into the adhesive to form alayer of beads. The sheet was then cooled to room temperature, and anyloose beads were removed with a vacuum. The article at this stage is anexample of optical elements 12 embedded in a heat softenable adhesive 34on a carrier 36.

A cyan color composition (Example 1—Bayhydrol® VPLS 2058 13.83%;CAB-O-JET® 250C 20.22%; Dow Corning Z-6011 0.35%; Desmodur® 2655 0.58%;oleic acid 0.05%; and ethanol 64.98%—the amounts are percents of thetotal wet weight of the composition) and a black color composition(Example 2—Bayhydrol® VPLS 2058 13.83%; CAB-O-JET® 300 20.22%; DowCorning Z-6011 0.35%; Desmodur® 2655 0.58%; oleic acid 0.05%; andethanol 64.98%—the amounts are percents of the total wet weight of thecomposition) were coated with the coating bar gap set at 55 um(calculated from the bottom of the valley between the beads).

The coated article was then heated to about 65° C. for about 3 minutes.The temperature was then raised to about 90° C. and maintained for about2 minutes. A colored layer having a weight of about 2 g/m² was formed.The article at this stage is an example of a colored layer 18 betweenoptical elements 12 embedded in a carrier web 32.

The article was observed from the surface of the exposed beads, using anoptical microscope at a magnification of 200×. A recorded image fromExample 1 can be seen in FIG. 6. As seen in FIG. 6, some of the ceramicbeads have pigment clusters on the tops (an exemplary bead with pigmentclusters is noted as bead 61) and some do not (an exemplary bead withoutvisible pigment clusters is noted as bead 63).

The samples were then vapor coated with aluminum. The article at thisstage is an example of a reflective layer 16 formed on a colored layer18 between optical elements 12 embedded in a carrier web 32.

After vapor coating, the samples were then coated with a bindercomposition (Vitel® 3580 87.48%; Desmophen® 670BA 3.82%; BiCat® 81080.03%; Dow Corning Z-6011 1.37%; and Desmodur® Z4470 7.30%—the amountsare percents of the total wet weight of the composition) at a solidcoating weight of 60 g/m², then cured at 80° C. for about 1 minute, andthen moved to an oven at 125° C. for about 2 minutes. The article atthis stage is an example of a binder layer 14 disposed on a reflectivelayer 16 formed on a colored layer 18 between optical elements 12embedded in a carrier web 32.

The coated samples were then laminated with 80/20 TC fabric at 160° C.for about 30 seconds. The article at this stage is an example of asubstrate 20 disposed on a binder layer 14, on a reflective layer 16formed on a colored layer 18 between optical elements 12 embedded in acarrier web 32. After about 12 hours, the fabric (which can beconsidered the substrate 20) was stripped off the article and thearticle was tested.

Examples 1 and 2 were tested using EN471 for their reflective brightnessat all angles and at an observed angle of 0.02/actual angle of 5 after0, 5, 10, and 15 washing cycles. The results for all angles can be seenin Table 1 below and the results for the observed angle of 0.2 and anactual angle of 5 after 0, 5, 10, and 15 washing cycles is shown in FIG.6B. The color of Example 2 was also analyzed using ASTM E1164-9.4 andthe color analysis can be seen in FIG. 8.

TABLE 1 Observed Actual Angle Angle EN471 Spec Example 1 Example 2 0.2 5330 424.54 413.18 0.2 20 290 361.49 369.51 0.2 30 180 281.25 275.37 0.240 65 129.92 143.89 0.33 5 250 306.1 294.61 0.33 20 200 262.82 269.750.33 30 170 210.34 221.26 0.33 40 60 106.46 128.58 1 5 25 33.5 35.87 120 15 30.89 33.92 1 30 12 22.53 22.26 1 40 10 12.97 27.63 1.5 5 10 19.3321.92 1.5 20 7 17.08 21.29 1.5 30 5 15.07 21.85 1.5 40 4 8.26 9.44

Examples 3 through 7

Optical elements embedded in a heat softenable polymer on a carrier weremade as described in Examples 1 and 2.

Color compositions as seen in Table 2 below were coated on the beads toform colored layers as described in Examples 1 and 2. The coating weightof the color composition was about 10 g/m².

TABLE 2 Example 3 Example 4 Example 5 Example 6 Example 7 % wt in % wtin % wt in % wt in % wt in wet wet wet wet wet formula formula formulaformula formula J-color 12.05 15.01 18.07 21.06 24.15 JCF10D Desmophen9.29 7.29 5.31 3.27 1.28 670 Desmodur 6.67 5.34 4.05 2.71 1.39 NZ1Dynasylan 0.85 0.85 0.86 0.85 0.84 1122 Bichat 0.01 0.01 0.01 0.01 0.018108 CX100 1.21 1.50 1.81 2.11 2.42 Toluene 34.96 35.00 34.94 34.9934.95 Ethyl 34.96 35.00 34.94 34.99 34.95 acetate total 100.00 100.00100.00 100.00 100.00

An aluminum coating, binder layer, and substrate were formed on thesamples as described in Examples 1 and 2. The substrate was removedafter 12 hours (as in Examples 1 and 2) and then the samples weretested. Examples 3 through 7 were tested with EN471 at 5/0.2 angles.FIG. 7 shows the brightness at 5/0.2 angles as a function of the pigmentloading of the samples. Table 3 shows the brightness at all angles forExample 4. The color of Example 4 was also analyzed using ASTM E1164-9.4and the color analysis can be seen in FIG. 8.

TABLE 3 Observed Angle Actual Angle EN471 Spec Example 4 0.2 5 330 380.60.2 20 290 364.81 0.2 30 180 274.98 0.2 40 65 122.63 0.33 5 250 285.480.33 20 200 268.57 0.33 30 170 209.52 0.33 40 60 101.71 1 5 25 31.88 120 15 31.02 1 30 12 23 1 40 10 16.11 1.5 5 10 17.04 1.5 20 7 16.6 1.5 305 14.08 1.5 40 4 9.14

Example 8

Optical elements embedded in a heat softenable polymer on a carrier weremade as described in Examples 1 and 2. A cyan color composition (JColor®JCF10D 24.06%; Desmophen® 670 7.07%; Desmodur® NZ1 5.40%; BiCat® 81080.02%; CX100 2.41%; toluene 29.95%; and ethyl acetate 29.95%—the amountsare percents of the total wet weight of the composition) was coated withthe coating bar gap set at 55 um (calculated from the bottom of thevalley between the beads). The coated article was then heated to about65° C. for about 3 minutes to flash off the low flash point solvent(ethanol). The temperature was then raised to about 90° C. andmaintained for about 2 minutes. The coating weight of the colorcomposition was about 9 g/m².

A layer of clear polymer solution (Desmophen® XP 2501 3.16%; Desmodur®NZ1 1.73%; Dynasylan® 1122 0.15%; and ethyl acetate 94.96%—the amountsare percents of the total wet weight of the composition) was coated onthe exposed surface of the color layer (to provide an article similar tothat seen in FIG. 1E) at a coating bar gap set at 55 um (calculated fromthe bottom of the valley between the beads). The coated article was thenheated to about 65° C. for about 3 minutes to flash off the low flashpoint solvent (ethanol). The temperature was then raised to about 90° C.and maintained for about 2 minutes. A clear layer having a coatingweight of about 3 g/m² was formed.

An aluminum coating, binder layer, and substrate were formed on thesamples as described in Examples 1 and 2. The substrate was removedafter 12 hours (as in Examples 1 and 2) and then the sample was testedwith EN471 reflective brightness at all angles. The color was alsoanalyzed using ASTM E1164-9.4. The reflectivity can be seen in Table 4below; and the color analysis can be seen in FIG. 8.

Example 9

Optical elements embedded in a heat softenable polymer on a carrier weremade as described in Examples 1 and 2. A layer of clear polymer solution(Vitel® 3580 9.1%; Desmodur NZ1 0.9%; and ethyl acetate 90.0%—theamounts are percents of the total wet weight of the composition) wascoated on the exposed surface of the optical elements with the coatingbar gap set at 55 um (calculated from the bottom of the valley betweenthe beads). The coated article was then heated to about 65° C. for about3 minutes to flash off the low flash point solvent (ethanol). Thetemperature was then raised to about 90° C. and maintained for about 2minutes. A clear layer having a coating weight of about 5 g/m² wasformed.

A color composition (JColor® JCF12 18.1%; Desmophen® 670BA 5.3%;Desmodur® NZ1 4.1%; CX100 1.8%; and ethyl acetate 69.9%—the amounts arepercents of the total wet weight of the composition) was coated with thecoating bar gap set at 55 um (calculated from the bottom of the valleybetween the beads). The coated article was then heated to about 65° C.for about 3 minutes to flash off the low flash point solvent (ethanol).The temperature was then raised to about 90° C. and maintained for about2 minutes. The coating weight of the color composition was about 8 g/m².

A second layer of clear polymer solution (Vitel® 3580 9.1%; Desmodur NZ10.9%; and ethyl acetate 90.0%—the amounts are percents of the total wetweight of the composition) was coated on the exposed surface of thecolor layer (to provide an article similar to that seen in FIG. 1F) at acoating bar gap set at 55 um (calculated from the bottom of the valleybetween the beads). The coated article was then heated to about 65° C.for about 3 minutes to flash off the low flash point solvent (ethanol).The temperature was then raised to about 90° C. and maintained for about2 minutes. A clear layer having a coating weight of about 3 g/m² wasformed.

An aluminum coating, binder layer, and substrate were formed on thesamples as described in Examples 1 and 2. The substrate was removedafter 12 hours (as in Examples 1 and 2) and then the sample was testedwith EN471 at all angles. The color was also analyzed using ASTME1164-9.4. The reflectivity can be seen in Table 4 below; and the coloranalysis can be seen in FIG. 8.

TABLE 4 Observed Actual EN471 Angle Angle Spec Example 8 Example 9 0.2 5330 457.06 437.64 0.2 20 290 411.87 408.76 0.2 30 180 260.65 255.41 0.240 65 102.04 109.17 0.33 5 250 341.21 321.65 0.33 20 200 313.57 292.250.33 30 170 217.81 195.12 0.33 40 60 92.69 67.56 1 5 25 38.31 39.5 1 2015 39.41 45.38 1 30 12 29.8 46.06 1 40 10 24.2 19.42 1.5 5 10 21.9120.33 1.5 20 7 20.96 21.21 1.5 30 5 21.8 20.77 1.5 40 4 12.01 15.21

Thus, embodiments of exposed lens retroreflective articles aredisclosed. One skilled in the art will appreciate that the presentdisclosure can be practiced with embodiments other than those disclosed.The disclosed embodiments are presented for purposes of illustration andnot limitation, and the present disclosure is limited only by the claimsthat follow.

What is claimed is:
 1. An exposed lens retroreflective articlecomprising: a binder layer; a layer of spaced apart optical elementsthat is partially embedded in the binder layer, wherein each opticalelement within the layer of optical elements has an embedded portioncomprising a back surface; a colored layer comprising pigment that islocated at least between the spaced apart optical elements; and areflective layer that is located functionally behind the layer ofoptical elements and the colored layer; wherein at least one pigmentcluster is present on the back surface of an optical element; andwherein the article exhibits a retroreflectivity at 5/0.2 angle of atleast about 50 cd/lux/m².
 2. The article of claim 1, wherein the coloredlayer is also at least partially located between the layer of opticalelements and the reflective layer and comprises the at least one pigmentcluster, and wherein the colored layer has a thickness that is greaterbetween adjacent optical elements than between the layer of opticalelements and the reflective layer.
 3. The article of claim 1, whereinthe colored layer has an average thickness between the spaced apartoptical elements ranging from greater than 0.1 times the averagediameter of the optical elements to 0.75 times the average diameter ofthe optical elements.
 4. The article of claim 1, wherein the coloredlayer has a non-uniform thickness.
 5. The article of claim 1, whereinthe colored layer is non-reflective.
 6. The article of claim 1, furthercomprising a clear layer.
 7. The article of claim 5, wherein the clearlayer has a thickness of from about 0.01 μm to about 20 μm.
 8. Thearticle of claim 5, wherein the clear layer is disposed on the coloredlayer.
 9. The article of claim 5, wherein the clear layer is disposedbetween the colored layer and the reflective layer.
 10. The article ofclaim 5, wherein the clear layer is disposed in at least one of thefollowing locations: on the colored layer, and between the colored layerand the reflective layer.
 11. The article of claim 1, wherein the binderlayer comprises a polymeric material made from a monomeric or oligomericunit selected from the group consisting of urethane, ester, ether, urea,epoxy, carbonate, acrylate, acrylic, olefin, vinyl chloride, amide,alkyd, and combinations thereof.
 12. The article of claim 1, wherein thebinder layer has an average thickness of about 30 to 150 μm.
 13. Thearticle of claim 1, wherein the pigment comprises a nanopigment.
 14. Thearticle of claim 1, wherein the colored layer is at least partiallypenetrated by the optical elements.
 15. The article of claim 1, whereinthe article exhibits a retroreflectivity at 5/0.2 angle of at leastabout 330 cd/lux/m².
 16. The article of claim 1, wherein the articleexhibits a retroreflectivity at 5/0.2 angle of at least about 100cd/lux/m² after 15 washes.
 17. The article of claim 1, wherein thecolored layer comprises a fluorescent yellow pigment, and the articleexhibits a fluorescent yellow color.
 18. The article of claim 1, whereinthe colored layer comprises a fluorescent red-orange pigment, and thearticle exhibits a fluorescent red-orange color.
 19. A method of makingan exposed lens retroreflective article comprising, the methodcomprising: partially embedding a plurality of optical elements in acarrier web; applying a color composition to the exposed surfaces of theoptical elements, wherein the color composition comprises: pigmenthaving an average size from about 1 nm to about 1000 nm; and at leastone polymer, wherein the color composition is applied to the exposedsurfaces of the optical elements to result in at least one pigmentcluster being present on an exposed surface of an optical element, suchthat at least one pigment cluster is present on the back surface of anoptical element of the resulting article; applying a reflective materialto the exposed surfaces of the optical elements and the applied colorcomposition; and applying a binder composition to form a binder layer;wherein the article exhibits a retroreflectivity at 5/0.2 angle of atleast about 100 cd/lux/m² after 15 washes.
 20. An exposed lensretroreflective article comprising: a binder layer; a layer of spacedapart optical elements that is partially embedded in the binder layer,wherein each optical element within the layer of optical elements has anembedded portion comprising a back surface; a colored layer comprisingpigment that is located at least between the spaced apart opticalelements; and a reflective layer that is located functionally behind thelayer of optical elements and the colored layer; wherein at least onepigment cluster is present on the back surface of an optical element;and wherein the article exhibits a retroreflectivity at 5/0.2 angle ofat least about 100 cd/lux/m² after 15 washes.